Tag Archives: pest

World’s first genetically-engineered moths released in the wild

Could genetically-modified pests control themselves? New research aims to prove that yes, they can.

Image credits Mike Pennington.

The study, led by Anthony Shelton, a professor at Cornell University’s Department of Entomology, describes the creation and successful release of gene-edited diamondback moths into an open field setting in collaboration with British biotechnology company Oxitech.

Engineered for failure

“The diamondback moth is a global pest that costs $4-5 billion annually and has developed resistance to most insecticides, making it very difficult to manage,” says Dr Neil Morrison of Oxitec, the study’s corresponding author.

Diamondback moths (Plutella xylostella) is one of the main pests for crops in the brassica family which includes cauliflower, cabbage, broccoli, and canola. Certain populations of diamondback moths have shown very stubborn resistance to synthetic insecticides in many settings around the world (including Canada, Australia, the UK, the US, and China); under the right circumstances, their larvae can afflict entire crops, causing farmers to re-plow entire fields of (now-unmarketable) produce.

In order to address the threat, the team describes how they genetically-engineered the species to make it fail. They implanted two genes — a “self-limiting gene and a marker gene” according to Morrison — into the insect’s genome. These genes are meant to be handed down between generations creating “self-limiting moths [that] are non-toxic and non-allergenic.”

The idea behind this approach is for genetically-engineered male moths to make their way into the wide world and sow their wild oats with wild females. They’ll pass on the self-limiting genes, which prevent the female caterpillars from developing normally (so they die off).

But that’s just the theory — the team needed to test this approach in practice. Thus, they became the first group in the world to trial open-field releases of genetically-engineered moths, employing a “mark-release-recapture” method which has been long-used to study insect movements. Their findings suggest that their work is both effective and sustainable as a pest regulation strategy in the long term.

“Our research builds on the sterile insect technique for managing insects that was developed back in the 1950s and celebrated by Rachel Carson in her book, Silent Spring,” says Shelton. “Using genetic engineering is simply a more efficient method to get to the same end.”

“Professor Shelton’s team in Cornell conducted releases of self-limiting male moths alongside non-modified male moths, from the centre of the trial field planted with cabbage,” Morrison adds. “Traps throughout the field were set to recapture a proportion of released moths and, because they were marked with coloured powders, we were able to track their dispersal and lifespan in the field.”

After release, the gene-edited males behaved similarly to their unmodified counterparts in terms of distance traveled and survival. In a lab setting, the team adds, they were just as competent as unmodified males in competing for females. A mathematical model employed by the team further suggests that modified males would be sufficient to control the species’ population without the need for additional insecticides, making it sustainable and eco-friendly. Oxitec is currently evaluating where their technique can be used for the most benefit, in order to organize follow-up studies.

The use of self-limiting insects isn’t novel here — the approach is already in use on Aedes aegypti mosquitoes in Brazil, Panama and the Caribbean in a bid to control the spread of malaria.

The paper “First Field Release of a Genetically Engineered, Self-Limiting Agricultural Pest Insect: Evaluating Its Potential for Future Crop Protection” has been published in the journal Frontiers in Bioengineering and Biotechnology.

Pests destroy around one quarter of our crops — even more in developing areas

If we want to be able to feed the world, we’d best pay closer attention to pests.

According to current estimates, the world population is 7.7 billion. It took over 200,000 years to reach the first billion, and only 200 more years to reach 7.7 billion. By 2100, even conservative estimates put the world population at 11 billion — all of which will have to be fed. Considering that today, over 800 million suffer from chronic undernourishment, feeding the population of tomorrow will be quite a challenge.

Our agricultural productivity has increased dramatically in the 20th century, in a period often called “the Green Revolution.” Norman Borlaug, the “father” of the Green Revolution and the most prominent scientist associated with the movement, is credited with personally saving over 1 billion lives through his work.

However, with no other such revolution in sight, we will need to optimize production and reduce losses as much as possible — and one of the most important problems to consider are pests.

Pests and pathogens are an integral part of agriculture. They’ve been around since mankind has been growing crops, coevolving with agricultural plants. However, that’s not to say that we can’t do anything to fight them. Different methods have been employed, with varying degrees of success. But before we can talk about large-scale campaigns against pests, we first need to understand the big picture.

This is exactly where the new study comes in. Serge Savary, a researcher working at the French National Centre for Scientific Research, and colleagues, took on the gargantuan task of measuring global crop losses caused by pests and pathogens. They focused on the five most popular crops: wheat, rice, maize, potato, and soybean. Together, these crops make up almost half of mankind’s calorie consumption.

They found that at a global level, pets destroy:

  • 21.5% of wheat crops;
  • 30% of rice crops;
  • 22.5% of maize crops;
  • 17.2% of potato crops; and
  • 21.4% of soybean crops.

This type of data is extremely valuable, especially as standardized information is difficult to compile across different regions and crops — and there is little in the way of good news.

All in all, almost one-quarter of this food is completely lost — and to make matters even worse, the highest losses are associated with regions with fast-growing populations and which are already struggling with malnutrition. These are also areas frequently hit by emerging or re-emerging pests and diseases.

Researchers hope that their work will serve as a guideline for policymakers and farmers alike. At a global scale, if we want to be able to feed the world, we need quick and efficient interventions in these areas.

There’s also another problem, a common culprit: climate change. It’s clear that climate change will affect plant-pathogen interactions, but it’s much less clear in what way. While they did not study this directly, Savary and colleagues quote another study, which ultimately concludes that “climate change will bring, above all, surprises.” Quite likely, they won’t be pleasant surprises.

The study has been published in Nature. DOI: 10.1038/s41559-018-0793-y

Insect damage to crops will drastically increase due to climate change

As if we didn’t have enough problems with climate change, here’s a new one: it will favor crop-devouring pests, bringing more agricultural damage in the coming years.

A modern plague

As anyone working in agriculture will tell you, pests can be absolutely devastating. Already, pests are eating the equivalent of 1 in every 12 loaves of bread, but things are about to get much worse. In a new study published in Science, researchers analyzed the effect climate change has on insects — particularly, pests. They found that rising temperatures accelerate the metabolism of these insects, prompting them to eat more and grow their populations. In other words, future bugs will be hungrier and more numerous.

They started with robust climate projection data, working on the assumption that there will be a 1.7C-2C global warming by the end of the century — a likely scenario, even if all the countries in the world achieve their Paris-mandated agreements (something which certainly isn’t a guarantee). They used crop yield statistics to see how much damage bugs are currently causing and worked on insect metabolic rates and other biological information to see how rising temperatures will affect the insects and, consequently, crops.

They found that results are not uniform, and areas with temperate climates (like most of Europe) will be hit the worst. By the end of the century, eleven European countries are predicted to see 75% or more in insect-induced wheat losses. The U.K., Denmark, Sweden, and Ireland are among those most affected.

“In some temperate countries, insect pest damage to crops is projected to rise sharply as temperatures continue to climb, putting serious pressure on grain producers,” said Joshua Tewksbury, co-lead author of the research and a director of Future Earth, an international research network for global sustainability.

Global problems

North America and Asia won’t be spared. The US, currently the world’s largest maize producer, could suffer a 40% increase in insect-induced maize losses under current climate warming trajectories — and even more if temperatures rise over 2C. This translates to losses of over 20 million tons annually. Meanwhile, one-third of the world’s rice production comes from China, where future insect-induced losses could top 27 million tons annually.

“On average, the impacts on insects adds up to about a 2.5 percent reduction in crop yield for every degree C increase in temperature – for context, this is about half the estimated direct impact of temperature change on crop yields, but in north temperate areas, the impact of increases insect damage will likely be greater than the direct impact of climate on crop yields” said Tewksbury, who is also a research professor at CU Boulder.

The study advises crop growers to start adapting, and consider selecting for heat and pest-resistant crops, as well as new crop rotation patterns. They also warn that, in some areas, greater pesticide use may become necessary to ensure food security — even considering the possible associated health and environmental damage.

The study was published in Science.

Blue visible light can be used as insect killer, research shows

Keeping insects at bay is more than eliminating a simple nuisance – in many some parts of the world, it’s vital. Malaria, an infectious mosquito-borne disease kilss over 500,000 people every year, and the disease could be kept under control if the mosquito population was kept under control; this is where this study steps in.

Some insects provide many environmental services, but many others are simply regarded as pests. For farmers working the land or for people in the poorer areas, insects can be a huge problem, causing major economic damage, and sometimes causing life-threatening diseases. Many solutions have been proposed for such situations, but for the most part, farmers still use insecticide to kill pests and people in Africa use bed sheets and other physical protection against mosquitoes. But insecticides are toxic to humans and bed sheets only get you so much, so a better solution would be more than welcome. This is where blue light comes in.

Japanese researchers from Tohoku University describe in the journal Scientific Reports that certain wavelengths of visible light are lethal to certain species of insects. For instance, blue light (wavelength = 467 nm; lights of different wavelenghts have different colors in the spectrum) was nearly 100% lethal to fruit fly pupae, while ultraviolet A light (wavelength = 378 nm) was only about 40% lethal.

Image source: Hori et al, 2015.

They went on and found that pupae of the London Underground mosquito (Culex pipiens molestus) were killed by violet/indigo light (417 nm), while pupae of the confused flour beetle (Tribolium confusum) were killed by several different wavelengths of light, ranging from violet to blue. Of course, in nature, insects are also subjected to these wavelengths, but in the study, they were subjected to much more light than they would have naturally.

“We also investigated the lethal effects of various bluelight wavelengths (404–508 nm) on pupae of the mosquito Culex pipiens molestus. Blue light irradiation was lethal to mosquito pupae, although their tolerance was higher than that of D. melanogaster pupae”, researchers write.

Researchers also suggest that different wavelengths could kill different bugs, and that this technology could actually be used practically in many environments. The key thing here is that people would be able to selectivelly kill pests, while leaving friendly ones unharmed. It would also reduce pesticide use, making foods less dangerous for humans, but the downside is that it would take a lot of energy. Illuminating whole fields with blue LEDs is no easy feat, and I’m not sure how the economic side factors into this one (this wasn’t tackled in the study). If the price is lower, comparable, or even just a bit higher, then it would be avantageous to use. If it’s much higher, I’m not sure farmers would adopt the method.

Also, if you want to keep multiple insects at bay, you have to use multiple types of LEDs. UV light is by far the most efficient type of light, but it can also be harmful to mammals. All in all, a very interesting find, but there’s still a way to go before this can be used practically.

Journal Reference: Masatoshi Hori, Kazuki Shibuya, Mitsunari Sato & Yoshino Saito. Lethal effects of short-wavelength visible light on insects. Via Nature.

Amazing fungus gnat larvae group together to form a ‘snake’ [VIDEO]

Fungus gnats (Bradysia species) – also known as dark-winged fungus gnats, are small, mosquito-like insects often found in homes and offices, usually in the vicinity of houseplants. The larvae that hatch are legless, with white or transparent bodies and shiny black heads. From the first glimpse you’ll notice they’re not the prettiest sight, but what they lack in looks, they make up in cleverness.

The fungus gnat larvae are incredibly vulnerable when alone; they’re puny, non-poisonous and practically at the mercy of predators – basically anything larger than them. To survive, the larvae have adapted a group behavior in which they join together by the hundreds to form a slimy, moving mass. The video embedded in this post illustrates this behavior. At first, you might be fooled to think you’re watching a snake (a two-headed snake?), but once the video zooms in all hell breaks loose.

While this instance of fungus gnat larvae behavior is very clever (or grouse), they’re consider serious pests and can cause severe damage to both houseplants and commercial crops. Some fungus gnat larvae are known for their propensity to feed on the roots and lower stem tissues of plants. These feeding habits stunt and might kill affected plants.

Poisoning rats is poisoning birds

Law-makers in Canada and the US are making moves to restrict rat poisons based on blood thinners as studies show that the toxins accumulate in birds of prey and other animals.

Blood thinning and rats

For many people, rats are the worst pets, and they will use all sorts of methods to get rid of them; one method, really common throughout North America is anticoagulant rodenticides (ARs), which work like the human blood-thinning drug warfarin. Warfarin is an anticoagulant that can be used as a poison itself, but it is less likely to accumulate in animals than its successors, which are far more dangerous.

But there was an unexpected effect.

“It seems that every time anybody goes out and gets a bunch of dead birds of prey and looks at their livers, they find surprisingly high incidence of these compounds,” says John Elliott, an ecotoxicologist at Environment Canada in Delta.

Colateral damage

In a study conducted over 130 dead birds, researchers found that “virtually 100%” of the owls and a large proportion of the hawks had residues of at least one second-generation AR in their livers. The discoveries were announced at the 2012 meeting of the North American division of the Society of Environmental Toxicology and Chemistry in Long Beach, California.

“From a regulatory point of view [second-generation ARs] are ‘PBT’,” he says. “Persistent, bioaccumulative and toxic.”

Presumable, the birds eat rats, but this can also happen to smaller birds: insects eat the bait and birds then eat the insects. The good news is that the population was quite responsive to the news, and hopefully, they will avoid using AR as poisons.

“We know consumers can comprehend and respond to warnings about wildlife exposures,” says Fairbrother. A few years ago, she adds, a survey asked consumers whether they knew that rodenticides could affect non-target wildlife. “They had no idea,” she says. But once alerted, their response was, “Now that I know, I’m going to be a lot more careful about how I use them”.

Climate change in NY likely to increase diseases

As global warming is starting to be felt more and more, secondary side effects are being predicted and reported throughout the whole world. Recently, a new report published by researchers from Cornell, Columbia University, and Hunter College painted a dire picture for New York, predicting disproportionate effects of climate change in the following decades, which will lead to a number of problems.

New York, which is a northern state is already warming much faster than the rest of the globe (approximately twice as fast), and these changes will affect every single aspect of New York’s economy and health. Everything from agriculture to ski resorts will suffer from droughts, sea level rise, floods, etc, and once this is done, unchanging it will be borderline impossible.

Furthermore, a number of diseases are likely to show up or increase as well. As the climate gets warmer, it can support numerous pests, such as the mosquito, carrying a large number of diseases, including malaria.